Electric-heating element



ep 19 7 w. c. MERRILL ELECTRIC HEATING ELEMENT Filed June 2. 1926INVENTOR.

BY RREN c. MERRILL.

WMUQ /S A TORNEY.

Patented Sept. 27, 1927.-

UNITED STATES WARREN C. MERRILL, F ALAMEDA, CALIFORNIA,

ELECTRIC-HEATING ELEMENT.

Application filed June 2, 1926. Serial No. 113,120.

This invention relates to electric heating elements as used principallyin water heaters and the objects of the invention are to provide asimple more'lasting construction of such elements as well as one havinggreater eificiency for the heating of fluids than prior devices of thiskind.

My element is preferably of the plug type adapted for insertion into thecasing and Water space of an electric water heater and is illustrated inthe following drawings in which:

Figure 1 is an outside view of the complete device ready for screwinginto the heater.

Flgure 2 is a View similar to the view of Figure l but shown partly insection.

Fi ure 3 is an enlargedcross section of the evice taken along the line3-3 of Figare 2, while Figure 4 is a similarly enlarged longitudinalsection taken at any point through the windings of the device.

In further detail the device comprises a screw plug or head 1, adaptedfor securing in an opening of a heater casing by means of a pipe thread2 or otherwise, while extending from the plug is an elongated resistanceassemblage enclosed in a tube 3.

This tube 3 isg'preferably of metal and tapered ofi at an angle at bothends as indicated, with one of the tapered ends extending into a matingrecess formed in the" head 1, and there firmly secured in place by 1 anydesired means, tho shown to be welded or soldered as at 4.

With the tube angularly cut and mounted as described it will be observedthat a passage way indicated by the arrows is open at all times from oneend to the other for free circulation of any fluid into which theelement might be inserted.

Within the tube 3 is spaced a smaller tube.

5 preferably of polygonal cross section as indicated in Figure 3 withfrom three to an number of sides, and around which po ygonal tube aspiral of resistance wire 6 is wrapped.

This wire 6 is preferably of flat section as indicated clearly in Figure4 and arranged in several layers insulated from the two tubes 3 and 5 bymeans of several. layers of sheet insulation 7, preferably of the micavariety lying between the wires and the respective tubes 3 and 5 as wellas betweenany several layers of the resistance coils as denoted at 7'.

wire are wound over. these other layers of insulation, all follow thesame angle and spacing but the coils have their windings staggered so asto bring the coils of one wrapping directly between the spacings of thenext layer of wires.

By theabove arrangement of insulation in sheets and staggered wires theinner sheets of insulation 7 become slightly undulateddue to thepressure thereagainstof the v staggered outer coils which aids inpreserving the coils from shifting laterally through the constantexpansion and contraction, though even with a sin 1e layer of resistancewire the tendency of WlIGS to shift is o'vercome due tothe use of thepolygonal J lnner .tube 5 around which the flat wlre is wrapped, for thewire firmly contacting the corners of the mica wrapped tube is quitefree adjacent all flat faces of the tube and where the expansion takesplace, without affecting the seating of, the wire on the high points ofthe tube.

The tube 5 after being completely wrapped as described is fitted snuglywithin the outer tube 3 and the open ends sealed by any desired means, asatisfactory method of effecting this being to first push some asbestospacking in the space between the tubes as indicated at 8 and thenfilling the remaining outer space with solder as at 9.

At the head end of thetube the terminal ends 10 and 10' of the wire arerespectively attached to suitable binding posts or screws 11 and 11'mounted in an insulating block 12 secured to the head 1 ,by screws orthe like as indicated.

In considering my electric heating element as above disclosed, it willbe'seen that it may be screwed into openings in a water compartment andthat owing to the peculiar construction it will not sufferdisarrangement through long use, and that upon heating up it causes aconstant circulation of water flowing from the plug end to the outer endthe larger efiective opening at the outer en insuring a current, and theangular out thereof overcoming interference of the water current fromother elements projecting into the heater below it.

I claim:

-1. An electric heating element comprising a head having a resistanceelement of tubular construction extending therefrom unsupported at itsouter end arranged to carry a flow of liquid through its tubular bodyfrom the head end for discharge at the outer end and said outer endbeing cut ofi at a bevel to the axis of the tubular body.

l2. An electric heating element for a fluid heater comprising anattaching head and a resistance coil enclosed in a tube extending fromand secured at one end only to said head, said tube being beveled at theend and seated in a pocket formed in the head.

3. In an electrical heating element of the character described, a pairof tubes spaced one Within the other, layers of resistance wire wrappedaroundthe inner tube and spaced therefrom and from the outer tube byinsulation, said resistance wire forming a plurality of spirals withcoils spaced and in staggered relation separated by flexible sheetinsulation positioned between the coils indented by the wrapping of thecoils thereon.

4. In an electrical heating element of the character described, a pairof tubes spaced one within theother, layers of resistance wire wrappedaround the inner tube and spaced therefrom and from the outer tube byflexible sheet insulation said inner tube being of polygonal crosssection.

5. In an electrical heating element of the character described, a pairof tubes spaced one within the other, layers of resistance wire wrappedaround the inner tube and spaced therefrom and from the outer tube byflexible sheet insulation said inner tube being of polygonal crosssection and said outer tube being of round cross section.

6. An electric tubular heating element adapted for insertion through theside of a Water container .in horizontal extension therein and providedwith a downwardly directed water inlet at one end to receive water intosaid element, and a discharge opening for said water at a point remotefrom said inlet when so positioned and whereby a current of water iscaused to flow through the length of said element upon heating the same.

7. An electric tubular heating element adapted for insertion through theside of a water container in horizontal extension therein and providedwith a downwardly directed water inlet at the end adjacent the containerand an upwardly directed water discharge outlet when so positioned andwhereby a current of water is caused to flow through the length of saidelement upon heating the same.

WARREN C. MERRILL.

